Isolated reversible mydriasis was associated with the use of nebulized ipratropium bromide: a case series using quantitative pupilometer in Korea.

BACKGROUND

Abnormal pupillary reactivity is a neurological emergency requiring prompt evaluation to identify its underlying causes. Although isolated unilateral mydriasis without accompanying neurological abnormalities is rare, it has occasionally been associated with nebulizer use. We aimed to quantitatively assess pupillary changes using a pupillometer in cases of isolated mydriasis, which has not been described in previous studies.

METHODS

We retrospectively analyzed patients who developed unilateral mydriasis after using an ipratropium bromide nebulizer using a prospectively collected database in the intensive care unit (ICU) between April 2019 and August 2020. An automated pupillometer (NPi-100 or NPi-200) was used for quantitative pupillary assessment. The Neurological Pupil index (NPi) value at the time of unilateral mydriasis was assessed, and the latency before and after the application of the ipratropium bromide nebulizer was measured.

RESULTS

Five patients with isolated mydriasis were identified (mean age, 68 years; male, 60.0%), none of whom had neurological abnormalities other than pupillary light reflex abnormalities. A quantitative pupillometer examination revealed that the affected pupil was larger (5.67 mm vs. 3.20 mm) and had lower NPi values (0.60 vs. 3.40) than the unaffected side. These abnormalities resolved spontaneously without treatment (pupil size, 3.40 mm; NPi, 3.90). The affected pupil had a prolonged latency of 0.38 seconds (vs. 0.28 seconds), which improved to 0.30 seconds with the resolution of the anisocoria.

CONCLUSIONS

In the ICU setting, it is important to keep in mind the ipratropium bromide nebulizer as the benign cause of unilateral mydriasis. Further, an automated pupilometer may be a useful tool for evaluating unilateral mydriasis.